Up until this week, state Sen. Deb Fischer (R) seemed headed to a decisive victory against former Sen. Bob Kerrey (D) in the race for the open U.S. Senate seatin Nebraska. Fischer has led by double-digits in the few public polls conducted in the state, and neither national party committee has spent any money on the race. However, three new polls released this week suggest that Kerrey has moved to within striking distance of the lead.
Two independent polls from Wiese Research Associates and Pharos Research Group, and an internal poll for Kerrey's campaign, found him within five points of Fischer. Meanwhile, Fischer's campaign responded with an internal poll showing the candidate ahead by a comfortable 16-point margin.
In races like that in Nebraska, with five or fewer polls released in the last three weeks, the HuffPost Pollster rating is based on the consensus of three respected election handicappers: the Cook Political Report, the Rothenberg Political Report and Larry Sabato's Crystal Ball. Since only four polls have been released in the last three weeks and the handicappers still see Fischer as the clear favorite, this race is still rated as "strong Republican."
Including Nebraska, there are 14 competitive Senate races this year. This unusually large number has left a good deal of uncertainty all year about which party will control the upper chamber in 2013.
The road to a majority is undeniably more difficult for Republicans, but they still have a viable path to 51 seats:
1.) Retain the Republican-held seats that are currently rated as "toss-ups": Indiana, Arizona and Nevada.
2.) Win the three Democratic-held seats in red states: Nebraska, North Dakota and Montana.
3.) Retain the Republican-held seat in Massachusetts while winning one Democrat-held seat in a battleground state: Virginia, Wisconsin, Ohio, Pennsylvania or Florida.
This scenario would leave the GOP the 51 seats needed for an outright majority. If Republican presidential nominee Mitt Romney is elected, the party would only need to win 50 seats, with Rep. Paul Ryan (R-Wis.) casting the tie-breaking vote as vice president.
However, the Republican candidates currently trail in the majority of the seats listed above, according to the HuffPost Pollster estimates, which include all available polls.
Here are the major developments in the key Senate races across the country.
We are still waiting on the release of the first independent poll since Richard Mourdock's rape remarks in Indiana, but two partisan polls released Friday can give us a rough idea of where the race stands. A poll sponsored by the Democratic Senatorial Campaign Committee(DSCC) found Rep. Joe Donnelly (D-Ind.) leading Mourdock 47 to 40 percent. However, an internal poll conducted for Mourdock's campaign found the race to be tied, but it also marked a slight drop in support for the candidate since his last internal poll from three weeks ago, in which he was ahead by three points. Donnelly now edges Mourdock by 0.6 points in the current HuffPost Pollster estimate, but that is subject to change when independent pollsters take the state's temperature.
In Massachusetts, Sen. Scott Brown (R) got his strongest result in weeks in a new Boston Globe/University of New Hampshire poll, showing him and Elizabeth Warren (D) tied at 47 percent, including voters that are leaning toward one candidate. Warren currently holds a narrow 3.4 percentage-point lead over Brown in the HuffPost Pollster estimate.
There continues to be a large disconnect in the polls in Pennsylvania, with some polls showing Sen. Bob Casey (D) leading Tom Smith (R) by comfortable margins and others showing the race to be within the margin of error. The National Republican Senatorial Committee and Majority PAC, a Democratic super PAC, have both made significant ad buys in the state in the last week. Casey currently holds a 5.2-point advantage in the HuffPost Pollster estimate.
Rep. Chris Murphy (D) seems to have solidified his lead over Linda McMahon (R) in Connecticut. He has led in 11 of the last 12 polls and has expanded his lead to 5.6 points in the HuffPost Pollster estimate.
This past week showed conflicting polls in the Missouri Senate race. A Mason-Dixon poll found Rep. Todd Akin (R-Mo.) trailing Sen. Claire McCaskill (D-Mo.) by just two points, while an internal poll conducted for McCaskill's campaign found her with a commanding 13-point lead. The DSCC has already started to cut ad spending in the state but the two candidates are still using heavily negative messaging against each other in the closing weeks of the race. McCaskill now leads Akin by 7.8 points in the HuffPost Pollster estimate.
When there are five or more available polls of a race conducted within the last three weeks, HuffPost Pollster rates the race as a "tossup" if the polling margin separating two candidates is less than 3 percentage points in the Pollster estimate. A race is designated as "leaning" toward one party if a candidate is leading by 3 to 6 percentage points. If a candidate is leading by more than 6 percentage points, the race is rated as "strongly" Democratic or Republican.
For more details and polls of all 33 Senate races, visit the HuffPost Pollster's Senate Outlook page.